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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 660731.0, MPI für Astronomie / Publikationen_mpia
Resolving the inner regions of the HD 97048 circumstellar disk with VLT/NACO polarimetric differential imaging
Authors:Quanz, S. P.; Birkmann, S. M.; Apai, D.; Wolf, S.; Henning, T.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Astronomy and Astrophysics
Volume:538
Start Page:id.A92
Audience:Not Specified
Abstract / Description:Context. Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. Because most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disks on these scales to constrain the conditions for planet formation. <BR /> Aims: Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD 97048 in polarized light. <BR /> Methods: We used VLT/NACO to observe HD 97048 in polarimetric differential imaging (PDI) mode in the H and Ks band. This technique offers high-contrast capabilities at very small inner working angles and probes the dust grains on the surface layer of the disk that act as the scattering surface. <BR /> Results: We spatially resolve the disk around HD 97048 in polarized flux in both filters on scales between ~0.1″-1.0″ corresponding to the inner ~16-160 AU. Fitting isophots to the flux calibrated H-band image between 13-14 mag/arcsec2 and 14-15 mag/arcsec2, we derive an apparent disk inclination angle of 34° ± 5° and 47° ± 2°, respectively. The disk position angle in both brightness regimes is almost identical and roughly 80°. Along the disk major axis the surface brightness of the polarized flux drops from ~11 mag/arcsec2 at ~0.1″ (~16 AU) to ~15.3 mag/arcsec2 at ~ 1.0″ (~160 AU). The brightness profiles along the major axis are fitted with power-laws falling off as ∝ r - 1.78 ± 0.02 in H and ∝ r - 2.34 ± 0.04 in Ks. Because the surface brightness decreases more rapidly in Ks compared to H, the disks becomes relatively bluer at larger separations, possibly indicating changing dust grain properties as a function of radius. <BR /> Conclusions: We imaged for the first time the inner ~0.1″-1.0″ (~16-160 AU) of the surface layer of the HD 97048 circumstellar disk in scattered light, which demonstrates the power of ground-based imaging polarimetry. Our data fill an important gap in a large collection of existing data that include resolved thermal dust and polycyclic aromatic hydrocarbon (PAH) emission and also resolved gas emission lines. HD 97048 therefore is an ideal test case for sophisticated models of circumstellar disks and a prime target for future high-contrast imaging observations. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (program number: 077.C-0106A).
Free Keywords:methods: observational; stars: formation; stars: pre-main sequence; protoplanetary disks; techniques: polarimetric
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://cdsads.u-strasbg.fr/abs/2012A%26A...538A..9...
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